半掺杂Pr0.5Ca0.5Mn1-xCrxO3体系的电荷有序和磁电阻效应

功能材料, 2007, 38(6): 891-894.

半掺杂Pr0.5Ca0.5Mn1-xCrxO3体系的电荷有序和磁电阻效应

李文娟 ^1, , 曹世勋 ^2, , 高湉 ^3, , 康保娟 ^4, , 袁淑娟 ^5, , 敬超 ^6, , 张金仓 ^7,

1.上海大学,物理系,上海,200444

2.上海大学,物理系,上海,200444

3.上海大学,物理系,上海,200444

4.上海大学,物理系,上海,200444

5.上海大学,物理系,上海,200444

6.上海大学,物理系,上海,200444

7.上海大学,物理系,上海,200444

基金项目: 高等学校博士学科点专项科研项目(20050280004) 上海市重点学科建设项目(T0104) 国家自然科学基金(10674092;10574087;10504019) 上海市自然科学基金(04JC14039)

关键词：锰氧化物 , 电荷有序 , 磁电阻效应

Charge-ordering and magnetoresistance effect in the half-doped Pr0.5Ca0.5Mn1-xCrxO3 system

研究了钙钛矿型半掺杂锰氧化物Pr0.5Ca0.5Mn1-xCrxO3(x=0、0.03、0.05、0.07、0.10)体系的输运性质、电荷有序和磁电阻效应.结果表明,Cr离子替代Mn位,增强了Pr0.5Ca0.5MnO3的铁磁性、金属电导和磁电阻值.在低掺杂情况下(x=0.03、0.05),Cr3+的掺杂使体系的铁磁性增强,当x＞0.05时(x=0.07、0.10),体系的铁磁性随x增大缓慢减弱.同时,随着掺杂量的增大,体系中的电荷有序相逐渐被抑制,磁电阻值也呈下降趋势,表明电荷有序相与磁电阻效应相关.Cr掺杂引起的各种磁耦合作用,包括Mn3+与Cr3+的铁磁双交换作用,Cr3+-Cr3+、Mn4+-Mn4+、Cr3+-Mn4+之间的反铁磁超交换耦合作用及相分离现象是产生上述结果的主要原因.

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